Bilateral, identical periodontal pockets will be produced around selected teeth in Rhesus monkeys. The pockets on one side of the jaws will be subjected to a currently accepted clinical therapeutic procedure, and the pockets on the other side left as unoperated controls. These pockets will be compared using histometric parameters at various time intervals after the therapeutic procedure. Thus, qualitative and quantitative information on the response of periodontal pockets to current therapeutic procedures will be obtained. The effect of long term, intermittent, mechanical injury on the progression of periodontitis will be evaluated histometrically in squirrel monkeys. Repetitive injury will be produced subjacent to experimentally induced marginal periodontitis on the mesial of the third bicuspid and distal of the second bicuspid on one side of the jaws. The corresponding surfaces on the contralateral sides of the jaws will have induced marginal periodontitis only for the same period of time, or the intermittent mechanical injury alone. A comparison between marginal periodontitis with and without the intermittent mechanical injury will determine whether there is any co-destructive factor effect. If there is such an effect, an attempt will be made to ascertain whether the co-destructive factors of marginal periodontitis and intermittent mechanical injury act in combination or independently.